What is a venomous (poisonous) snake bite?
A venomous (poisonous) snake bite is a bite or a puncture wound made by a snake that is capable of injecting, secreting, or spitting a toxin into the penetrated skin wound or, mucus membranes or the eyes where the toxin can be absorbed. In North America, there are about 25 species of snakes able to secrete toxin. However, non-native poisonous species are present in zoos and held in private homes or other areas by snake collectors. Consequently, almost any type of venomous snake bite can be encountered in the US. About 7,000 snake bites are reported in the US per year, but because snake bites are not required to be reported, it is estimated that up to 45,000 bites per year may occur with about 8,000 by poisonous snakes. The most common venomous snakes in the US are:
- cottonmouths/water moccasins, and
- coral snakes.
What is a nonvenomous (nonpoisonous) snake bite?
- A nonvenomous (nonpoisonous) snake bite is a bite or puncture wound made by a snake that is incapable of secreting a toxin. This should be distinguished from a dry bite.
- A dry bite is a bite by a venomous snake that does not inject any toxin.
- Even bites that are from a nonvenomous snake or are dry need to be evaluated as they can lead to significant tissue damage or infections.
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Poisonous Snake Bites
The U.S is home to many poisonous snakes, including these four snakes: coral snake, rattlesnake, water moccasin, and copperhead. Bite symptoms may include
- severe burning pain at the bite site,
- swelling that spreads out from the bite,
- trouble breathing,
- and changes in heart rate.
Bite severity depends on many factors, including the amount of venom injected, bite location, and a person's age and health. Seek immediate medical care if you think you've been bitten by a poisonous snake.
What are the symptoms of a venomous snake bite?
The symptoms of a venomous snakebite depend on the type of toxin(s) secreted into the bite or puncture wound, and in part, on how much toxin is present in the tissue. The types of symptoms produced can be grouped into four groups:
- Cardiotoxins: act on heart tissue
- Neurotoxins: act on nervous system tissue
- Cytotoxins: act on tissue at the site of the bite or on tissue that directly absorbs the toxin
- Hemotoxins: act on the blood coagulation system and may cause internal bleeding
Some toxins may cause more than one of these effects. Because of the various symptoms that can occur with venomous snake bites, the potential signs and symptoms to look for, as listed by the CDC include the following:
- A pair of puncture marks at the wound
- Redness and swelling around the bite
- Severe pain at the site of the bite
- Nausea and vomiting
- Labored breathing (in extreme cases, breathing may stop altogether)
- Disturbed vision
- Increased salivation and sweating
- Numbness or tingling around the face and/or limbs
Symptoms from these toxins are somewhat variable and may occur quickly or they may be delayed for hours, depending on the toxin type and the amount absorbed. In general, small children are more vulnerable to snake bites because the relative larger amount of toxin absorbed in relation to their smaller body size can make the toxin effect more potent.
Identification of the snake helps emergency health care professionals to both anticipate the potential symptoms, and it allows for more rapid and appropriate treatment of the venomous snake bite. A detailed description of the snake, a picture of the snake, or the snake itself (ideally dead!) will help identify the type of snake and the type of toxin. Time should not be wasted, however, in transporting the patient to an appropriate health care facility and do not put others in jeopardy of getting bitten.
How is a venomous snake bite diagnosed?
Any snake bite needs emergency evaluation. Identification of fang or bite marks is done, even if the snake is non-venomous, to determine
local trauma or tissue
damage at the site of the bite. Identification of the snake type by
description or picture, along with the circumstances of the bite and the surrounding environment
usually provides the health care professional a working diagnosis. For example,
a snake bite occurring in dry west
Texas is likely a rattlesnake bite, while a snake bite in a swampy area of the
US is likely a water moccasin. A zookeeper or private snake
owner/collector who is bitten will likely know the exact type of snake that caused the bite
or toxic spray (spitting cobras).
What is the
treatment for a venomous snake bite?
There are two phases in the treatment of snake bites.
- The emergency
treatment on site and during transport to an appropriate health care facility.
- Tthe health care facility stabilizes the patient, administers
antivenin if deemed necessary, and provides supportive treatment.
Phase one of snake bite treatment
In the past there have been many home remedies and treatments, along with
snake bite kits and other treatment methods, many of which have been shown to
make the effects of the snake bite worse. Consequently, the CDC has issued guidelines, used after the
threat of additional bites to the patient or others is eliminated, about what to
DO and what NOT TO DO if a snakebite occurs. The following are the
recommendations made by the CDC:
- Seek medical attention as soon as possible (dial 911 or call local Emergency
- Try to remember the color and shape of the snake, which can
help with identification and treatment of the snake bite.
- Keep still and calm. This can slow down
the spread of venom.
- Inform your supervisor (if the bite occurs at work).
first aid if you cannot get to the hospital right away.
- Lay or sit down with the bite below the level of the heart.
- Wash the bite
with soap and water.
- Cover the bite with a clean, dry dressing.
Do NOT do any of the following:
- Do not pick up the snake or try to trap it.
- Do not wait for symptoms to
appear if bitten, rather seek immediate medical attention.
- Do not apply a tourniquet.
- Do not slash the wound with a knife.
- Do not suck out the venom.
- Do not apply ice
or immerse the wound in water.
- Do not drink alcohol as a painkiller.
- Do not
drink caffeinated beverages.
Not included in the CDC recommendation is the bite
of the Australian elapid snake, also termed a sea snake, which is emergently
treated with a pressure bandage at the bite site with splinting and extremity
immobilization. Others suggest no use of electric shocks for any snake bite.
Phase two of snake bite treatment
The second phase of treatment consists of stabilization and supportive care,
and when medically indicated, administration of antitoxin (antivenin) specific for the snake species and a
booster vaccine. A good practice is to call your local poison control center or the
national Poison Help Line (1-800-222-1222), and also to consult a toxicologist and a
surgeon to help care for the patient. Certain patients may require surgical
treatment and admission to the hospital.
The treatment of non-venomous snake bites includes local wound care at the
site of the bite, removing snake teeth if left in the bite site, attending to
any trauma at the bite
site, and a tetanus booster if
needed. Some wounds may become infected and require additional treatment with
What are the complications of a venomous snake bite?
The complications of venomous snake bites can range from mild to severe.
pain and swelling at the bite site, vision damage (from sprays especially),
compartment syndrome (localized severe swelling that can damage or destroy nerves and
blood vessels, leading to muscle necrosis), infection, limb loss, gangrene,
sepsis, internal bleeding, cardiac damage, respiratory compromise,
and even death.
Can a snake bite be prevented?
Many snake bites can be prevented as most snakes are not aggressive toward
humans unless they sense danger. Consequently, avoidance of snakes usually
prevents a bite, so people should not try to handle, capture or threaten (for
example, tease with a stick) any snake. Statistical studies suggest that about
40% of all snake bites in the US occur in people that consumed alcohol drinks. If a
person's workplace involves areas known to be a habitat of snakes, wearing
thick pants, and wearing gloves may reduce the chances of a snake bite; or at least
it may reduce
the bite trauma and the amount of venom distributed.
What is the prognosis for a venomous snake bite?
Most snake bites, when quickly and appropriately treated, have a good
prognosis. If left untreated for various increasing lengths of time the
prognosis usually diminishes while the complications increase. Deaths are
unlikely as fewer than 10 deaths per year are due to snakebites in the US.
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Medically reviewed by Joseph Palermo, D.O.; American Osteopathic Board Certified Internal Medicine
"Venomous Snakes." CDC.gov. Updated July 1, 2016.
White, Julian, AM, MB, BS, MD, FACTM, Et Al. "Snakebites worldwide: Management." UpToDate.com. Updated Aug. 30, 2016.